This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:    3GPP third generation partnership project    RAT radio access technology    RRC radio resource control    RSCP received signal code power    RSRP reference signal received power    RX received    UE user equipment
In wireless communication, different wireless systems are available to provide different types of services and capabilities. Such wireless communication systems include wireless local area networks and cellular networks, among others. The cellular networks may include a variety of network types, such as Universal Terrestrial Radio Access Network (UTRAN), GSM/EDGE Radio Access Network (GERAN).
Cellular networks typically include multiple cells which allow a mobile user device to communicate while moving through the network. Often, a user device may be located in a geographic region serviced by multiple networks. The multiple networks may be arranged by their respective operators to be inter-operative. In this regard, to provide improved connection, one network operator may have an arrangement with another network operator to allow its users to switch to the other network if required avoid a disconnection from the network.
In this regard, inter-frequency and inter-RAT (radio access technology) cell reselection is performed according to agreed-upon priority algorithms. For example, the cell reselection algorithm for Evolved Universal Terrestrial Radio Access (E-UTRA) is defined in the current specification (3GPP TS 36.304), which is available at www.3gpp.org/ftp/Specs/html-info/36304.htm.
The current cell reselection methods have shortcomings which are addressed and improved by embodiments of the present invention.
As used herein, the phrase “priority layer” is used in a generic way to indicate either a RAT, or a frequency layer of RAT, or a group of frequencies of a RAT (e.g. a particular band).